The camera assembly is not completed until the measurement of the focal positions, such as the wide-angle position and the telephoto position, of the zoom lens, and the locating of the zoom lens are done. Generally speaking, the zoom lens is formed of a fixed cylinder, an outer movable cylinder, and an inner movable cylinder. The inner movable cylinder is provided therein with a shutter and a front group lens. In order to make sure that the zoom lens is precisely located to bring about a good focal effect, it is necessary to make use of an instrument to calibrate the zoom lens.
Such a measurement of optical position and a locating adjustment as described above involve a number of items, one of which is to do the locating adjustment of the lens disposed in the interior of the inner movable cylinder.
The lens of the inner movable cylinder is fixed by an outer frame which is fitted into a chain plate which is in turn pivoted to a rotary plate of the shutter. The outer frame is fastened in the interior of the inner movable cylinder by nuts and bolts. As the outer frame is turned, the lens is actuated to displace. When the zoom lens is set up in the camera body, the focusing lens is set at the position of infinite distance. Thereafter, the outer frame is driven by a tool to turn in conjunction with an instrument which is used to assist the measurement, so as to locate the lenses with precision.
Such a conventional way as described above for locating the lens is rather time-consuming in view of the fact that the measurement must be done repeatedly so as to set the focusing lens at the position of infinite distance.